Search Results (161)

The majority of studies of fungal utilization of chitosan are associated with the production of a specific enzyme, chitosanase, which catalyzes the hydrolytic cleavage of the macrochain. In our opinion, the development of approaches to obtaining materials with new functional properties based on non-destructive chitosan transformation by living organisms and their enzyme systems is promising. This study was conducted using a wide range of classical and modern methods of microbiology, biochemistry, and physical chemistry. The ability of the ascomycete Fusarium oxysporum Schltdl. to modify films of chitosan with average-viscosity molecular weights of 200, 450, and 530 kDa was discovered. F. oxysporum was shown to use chitosan as the sole source of carbon/energy and actively overgrew films without deformations and signs of integrity loss. Scanning electron microscopy (SEM) recorded an increase in the porosity of film substrates. An analysis of the FTIR spectra revealed the occurrence of oxidation processes and crosslinking of macrochains without breaking β-(1,4)-glycosidic bonds. After F. oxysporum growth, the resistance of the films to mechanical dispersion and the degree of ordering of the polymer structure increased, while their solubility in the acetate buffer with pH 4.4 and sorption capacity for Fe²⁺ and Cu²⁺ decreased. Elemental analysis revealed a decrease in the nitrogen content in chitosan, which may indicate its inclusion into the fungal metabolism. The film transformation was accompanied by the production of extracellular hydrolase (different from chitosanase) and peroxidase, as well as biosurfactants. The results obtained indicate a specific mechanism of aminopolysaccharide transformation by F. oxysporum. Although the biochemical mechanisms of action remain to be analyzed in detail, the results obtained create new ways of using fungi and show the potential for the use of Fusarium and/or its extracellular enzymes for the formation of chitosan-containing materials with the required range of functional properties and qualities for biotechnological applications. Full article

Construction wood has a high economic value, and its construction waste also has multiple consumption values. Natural wood has many advantages, such as thermal, environmental, and esthetic properties; however, wood sourced from artificial fast-growing forests is found to be deficient in mechanical strength. This shortcoming makes it less competitive in certain applications, leading many markets to remain dominated by non-renewable materials. To address this issue, various modification methods have been explored, with a focus on enhancing the plasticity and strength of wood. Studies have shown that hydrogen bonds in the internal structure of wood have a significant impact on its operational performance. Whether it is organic modification, inorganic modification, or a combination thereof, these methods will lead to a change in the shape of the hydrogen bond network between the components of the wood or will affect the process of its breaking and recombination, while increasing the formation of hydrogen bonds and related molecular synergistic effects and improving the overall operational performance of the wood. These modification methods not only increase productivity and meet the needs of efficient use and sustainable environmental protection but also elevate the wood industry to a higher level of technological advancement. This paper reviews the role of hydrogen bonding in wood modification, summarizes the mechanisms by which organic, inorganic, and composite modification methods regulate hydrogen bond networks, discusses their impacts on wood mechanical properties, dimensional stability, and environmental sustainability, and provides an important resource for future research and development. Full article

Theoretical calculations were performed to explore the heterogeneous nucleation mechanism of an Mg-Al alloy inoculated by a carbon-containing substance. The valence electron structure and cohesive energy of Al₄C₃ and Al₂C₂Mg crystals were calculated using the empirical electron theory of solids and molecules (EET). The binding energy of Al1-C2 bonds in Al₄C₃ is about 140.6 kJ/mol with a lower number of equivalent bonds. Correspondingly, the binding energy of Al2-C2 bonds is about 129.6 kJ/mol, and the number of equivalent bonds is high. The weak combination of the Al1 and C2 atomic layers might lead to the breaking of Al₄C₃, and then the remaining strong skeleton of the Al2-C2 structure will facilitate the formation of Al₂C₂Mg. Based on the calculating results, the atomic interaction mechanism to account for the heterogeneous nucleation of α-Mg by C inoculation is elaborated, which also provides insights into the essence of the overheating process and the influence of Al and Mn elements on the refinement efficiency of Al₂C₂Mg. Full article

Chitosan (CS)-based films have demonstrated significant potential as biodegradable packaging materials, but their suboptimal barrier and mechanical properties limit practical applications. In this study, CS/carboxymethyl cellulose (CMC) composite films were prepared using a NaOH/urea-based alkaline system. Optimal ratios (1.5% CS, 2% CMC, 2.5% NaOH, and 4% urea) were determined through an L₁₆(4⁴) orthogonal array design. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the formation of stable physical crosslinks between CS and CMC via hydrogen bonding. These interactions significantly enhanced mechanical properties (tensile strength: 46.08 MPa; elongation at break: 68%), improved thermal stability (maximum decomposition temperature: 304 °C), and superior barrier properties (water vapor transmission rate: 0.26 × 10⁻⁵ g/(m²·h·Pa); oxygen transmission rate: 1.12 × 10⁻⁴ g/(m²·s)). NaOH concentration exhibited the most pronounced influence on film performance. The composite film combines inherent biodegradability with excellent functional properties, offering a sustainable alternative to conventional petroleum-based packaging materials. Full article

LiFePO₄ (LFP) batteries are among the earliest commercialized and most discarded lithium-ion batteries. Although existing recovery technologies focus on the conversion of LiFePO₄ to Li₂CO₃, challenges associated with achieving near-full recovery and high-value products remain. This study proposes a strategy for the conversion of spent LiFePO₄ to LiF by mechanical chlorination coupled with a fluorination reaction. The optimum conditions were determined to be a ball-to-powder ratio (BPR) = 15, NH₄Cl:LFP = 3, H₂O₂ = 2.0 mL, rotation speed = 600 rpm, and grinding time = 12 h. Results showed that 97.14% Li was converted into LiCl by H₂O₂–NH₄Cl mechanical chlorination. When chlorinated intermediates were immersed in water, FePO₄ could be harvested, and 96.79% Li could be recovered as LiF with a purity of 99.50% after adding NH₄F. When Cl-functionalized renewable resin was used to exchange 99.89% F⁻, 0.63 g NH₄Cl per litre of LiF conversion residual liquid was derived. The favourable results were attributed to the ¹O₂ generated by H₂O₂, which had a strong electron affinity to break Li–O bonds and provided superior conditions for the combination of Li and Cl. During fluorination, the formation of LiF reduced the ion concentration, and the entropy decreased, contributing to the spontaneous reaction. Therefore, the proposed method paves the way for near-full recovery and high-value products of spent LiFePO₄. Full article

Flammability is a significant challenge in polymer-based strain sensing applications. In addition, the existing intrinsic flame retardant is not elastic at room temperature, which may potentially damage the flexible equipment. This study presents a series of flame-retardant ionic conductive elastomers (ICEs) (denoted as PCAIP_x) containing phosphorus from phytic acid (PA) and nitrogen from choline chloride (ChCl) with multiple hydrogen bonds synthesized using a simple and efficient one-pot UV-initiated radical copolymerization of a polymerizable deep eutectic solvent (PDES). The limiting oxygen index (LOI) value increased from 24.1% for the pure PCAI without PA to 38.3% for PCAIP_7.5. The SEM analysis of the residual char shows that the formation of the dense and continuous char layer effectively worked as a shield, preventing further decomposition of the undecomposed polymer inside while hindering the transmission of heat and mass and isolating the oxygen required for combustion. The hydrogen bonds’ cross-linked structure and phosphorus-containing elastomer demonstrate a superior elasticity (elongation at break of up to 2109%), durability, and tear resistance and excellent adhesive properties. Application of PCAIP_X in strain sensors showed that the elastomer has excellent cyclic stability and exhibited repeatable and stable resistance change signals in response to repetitive bending motions of the wrist, fingers, elbow, and knee. Consequently, this study provides a simple strategy for the development of a flame-retardant ICE which can effectively reduce fire hazards and potentially be applied in other fire-risk fields such as personal protection, firefighting, and sports equipment. Full article

Ionic liquids exhibit distinctive solvation and reactive properties, making them highly relevant for applications in energy storage, catalysis, and CO₂ capture. However, their complex molecular interactions, including proton transfer and physisorption/chemisorption, necessitate advanced computational efforts to model them at the atomic scale. This review examines key molecular dynamics approaches for simulating ionic liquid reactivity, including quantum-mechanical methods, conventional reactive force fields such as ReaxFF, and fractional force fields employed in PROTEX. The strengths and limitations of each method are assessed within the context of ionic liquid simulations. While quantum-mechanical simulations provide detailed electronic insights, their high computational cost restricts system size and simulation timescales. Reactive force fields enable bond breaking and formation in larger systems but require extensive parameterization. These approaches are well suited for investigating reaction pathways influenced by the local environment, which can also be partially addressed using multiscale simulations. Fractional force fields offer an efficient alternative for simulating significantly larger reactive systems over extended timescales. Instead of resolving individual reaction mechanisms in full detail, they incorporate reaction probabilities to model complex coupled reactions. This approach enables the study of macroscopic properties, such as conductivity and viscosity, as well as proton transport mechanisms like the Grotthuß process—phenomena that remain inaccessible to other computational methods. Full article

This study investigated the effects of calcium oxide (CaO) derived from eggshells on the gelation properties of surimi prepared from giant snakehead (Channa micropeltes). Surimi gels were enriched with CaO at concentrations of 0, 2, 4, 6, 8, and 10 µmol/100 g, and their physicochemical, rheological, and structural characteristics were evaluated. The optimal CaO concentration (6 µmol/100 g) significantly enhanced gel strength by 48.2%, breaking force by 26%, and deformation by 18% compared to the control (p < 0.05). Expressible moisture content decreased from 16.88% to 7.12%, while total sulfhydryl groups were reduced to 5.17 µmol/100 g. Rheological analysis revealed increased storage modulus (G′) and loss modulus (G″), indicating enhanced gel elasticity and viscosity during thermal processing. Scanning electron microscopy (SEM) demonstrated the formation of a compact, uniform gel network with fine pores at the optimal CaO concentration. SDS-PAGE analysis confirmed that CaO promoted transglutaminase (TGase) activity and TGase catalyzes the formation of cross-links between myosin heavy chain (MHC) and disulfide bonds. These results demonstrate the potential of eggshell-derived CaO as a sustainable, cost-effective additive to enhance surimi gel quality. Full article

It is known that the presence of redox-inactive metals in the active center of an enzyme has a significant effect on its activity. In this regard and for other reasons, the effect of redox-inactive metals on redox processes, such as electron transfer, oxygen and hydrogen atom transfer, as well as the breaking and formation of O–O bonds in reactions catalyzed by transition metals, has been widely studied. Many questions about the role of redox-inactive metals in the mechanisms of these reactions remain open. In this paper, the mechanism of catalysis by bi- and triple hetero-binuclear heteroligand complexes including Ni and redox-inactive alkali metals ((A) {Ni(acac)₂∙L²} and (B) {Ni(acac)₂∙L²∙PhOH} (L² = MSt (M = Li, Na, or K)) in the process of the selective oxidation of ethylbenzene by molecular oxygen into α-phenyl ethyl hydroperoxide is considered. The activity of A and B complexes towards O₂, ROOH, and RO₂^• radicals was studied. Based on kinetic data, we suggest that the high catalytic efficiency of B triple complexes in oxidation processes may be associated with the role of outer-sphere regulatory interactions, with the formation of stable supramolecular structures due to intermolecular H bonds. This assumption was confirmed using the AFM method. Prospects for studying catalysis by complexes ({Ni(acac)₂∙L²} and {Ni(acac)₂∙L²∙PhOH}) that are models of NiARD (Ni-Acyreductone dioxygenase) are discussed. Full article

Recently, researchers have been committed to boosting the environmental friendliness and functional performance of multifunctional additives. In this study, an eco-friendly methylbenzotriazole-amide derivative (MeBz-2-C18) was designed and synthesized, with ethylamine serving as the linkage between methylbenzotriazole and the oleoyl chain. The structure of MeBz-2-C18 was characterized by nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HR-MS), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). Subsequently, the storage stability and tribological behavior of MeBz-2-C18 and the commercial benzotriazole oleamide salt (T406) were comparatively evaluated. The covalently-bonded MeBz-2-C18 exhibits superior thermal stability, along with boosted storage stability and tribological performance in the synthetic base oil. Specifically, 0.5 wt.% addition of MeBz-2-C18 and T406 can reduce the average wear scar diameter (ave. WSD) by 21.6% and 13.9%, respectively. To further explore the micro-mechanism, the electrostatic potential (ESP) and worn surfaces were analyzed with scanning electron microscope-energy dispersive spectrometer (SEM–EDS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. The results show that MeBz-2-C18 possesses stronger adsorption on the metal surface, and its amide bond preferentially breaks during friction. This reduces the interfacial shear force and promotes the film formation of iron oxides, thus resulting in superior tribological performance. Full article

A simple short-flow thermo-mechanical treatment (TMT) named L-ITMT (consisting of three steps: solution, warm deformation, and solution) was applied to ultra-high-strength Al-10.0Zn-2.7Mg-2.3Cu alloy to study the influence of the deformation degree on the particle distribution, resolubility, microstructure evolution, recrystallization mechanism, formation and development of deformation bonds, and mechanical properties. Increasing the rolling deformation during the L-ITMT process can effectively break up the second phase at the grain boundary and promote its dissolution, which is beneficial to aging precipitation strengthening and improves the strength of the alloy. The dominant mechanism changes from recovery to recrystallization when the deformation degree reaches 80%. As the strain increases, the deformation band becomes flatter and eventually becomes nearly parallel to the RD direction, promoting the occurrence of geometric recrystallization or continuous recrystallization (CRX). Under high-strain conditions, the formation mechanisms of recrystallized grains include discontinuous recrystallization (DRX), CRX, and particle-stimulated nucleation (PSN), but the main contributions to the formation of large-area fine-grained bands are CRX and PSN. The results showed that as the deformation degree increased from 10% to 80%, the improvement of solid solubility and grain refinement in the short-flow TMT process increased the ultimate tensile strength (701 MPa), yield strength (658 MPa), and elongation (11.3%) of the alloy by 15.7%, 10.8%, and 842%, respectively. This shows that the short L-ITMT process has a synergistic effect in significantly improving the plasticity and maintaining the strength of this ultra-high strength Al-Zn-Mg-Cu alloy. Full article

We used density functional theory with a hybrid functional to investigate the structure and properties of [4H]_Si (hydrogarnet) defects in α-quartz as well as the reactions of these defects with electron holes and extra hydrogen atoms and ions. The results demonstrate the depassivation mechanisms of hydrogen-passivated silicon vacancies in α-quartz, providing a detailed understanding of their stability, electronic properties, and behaviour in different charge states. While fully hydrogen passivated silicon vacancies are electrically inert, the partial removal of hydrogen atoms activates these defects as hole traps, altering the defect states and influencing the electronic properties of the material. Our calculations of the hydrogen migration mechanisms predict the low energy barriers for H⁺, H⁰, and H⁻, with the lowest barrier of 0.28 eV for neutral hydrogen migration between parallel c-channels and a similar barrier for H⁺ migration along the c-channels. The reactions of electron holes and hydrogen species with [4H]_Si defects lead to the breaking of O–H bonds and the formation of non-bridging oxygen hole centres (NBOHCs) within the Si vacancies. The calculated optical absorption energies of these centres are close to those attributed to individual NBOHCs in glass samples. These findings can be useful for understanding the role of [4H]_Si defects in bulk and nanocrystalline quartz as well as in SiO₂-based electronic devices. Full article

In recent years, plasma medicine has developed rapidly as a new interdisciplinary discipline. However, the key mechanisms of interactions between cold atmospheric plasma (CAP) and biological tissue are still in the exploration stage. In this study, by introducing the reactive molecular dynamics (MD) simulation, the capsid protein (CA) molecule of HIV was selected as the model to investigate the reaction process upon impact by reactive oxygen species (ROS) from CAP and protein molecules at the atomic level. The simulation results show that ground-state oxygen atoms can abstract hydrogen atoms from protein chains and break hydrogen bonds, leading to the destruction of the disulfide bonds, C–C bonds, and C–N bonds. Furthermore, the generation of alcohol-based groups resulting from the impact of ROS can alter the hydrophobicity of molecules and induce damage to the primary, secondary, and tertiary structures of proteins. The dosage effects on the reaction processes and products induced by CAP are also explored with varying numbers of ROS in the simulation box, and the influences on the broken C–H, N–H, and C–N bonds are discussed. In this study, the computational data suggest that severe damage can be caused to CA upon the impact of ROS by revealing the reaction processes and products. Full article

Modified basalt microfiber-reinforced polyurethane elastomer composites were prepared by a semi-prepolymer method with two different silane coupling agents (KH550 and KH560) in this study. Infrared spectroscopy was used to quantify the degree of microphase separation and analyze the formation of hydrogen bonding in polyurethane. The interfacial surface and the morphology of fibers and composites from tensile fracture were examined by a scanning electron microscope. Further measurements were performed on an electronic universal testing machine for characterizing the mechanical properties of composites. Moreover, the loss factor and transmission loss of composite materials were obtained from dynamic thermomechanical analysis and acoustic impedance tube, respectively. The suitable concentrations in the modification of basalt fibers were established at 1% for KH550 and 1.5% for KH560. The best overall performance was obtained in KH550-BMF/PUE group, as the properties increased by 31% in tensile strength, 37% in elongation at break, and 21% in acoustic insulation. Full article

The study aimed to prepare complex gels of sonicated quinoa protein (QP) and polysaccharides, comparing the effects of different protein components and pH on gel properties. FTIR analysis demonstrated that the β-structure in protein at pH 7.0 was enhanced by ultrasonic treatment, which could promote the formation of a gel network. Moreover, XG-AG (gel prepared by xanthan gum and albumin) and XG-GG (gel prepared by xanthan gum and globulin) exhibited higher levels of disulfide bonds and free sulfhydryl groups in the gel, requiring more energy to break the intermolecular sulfide bonds during heating. Under the same heating conditions, the rheological properties and gel strength of XG-UQPG (gel prepared by xanthan gum and ultrasonically treated QP) were superior to those of XG-UGG (gel prepared by xanthan gum and ultrasonically treated globulin) and XG-UAG (gel prepared by xanthan gum and ultrasonically treated albumin). Additionally, XG-UGG (pH 7.0) demonstrated the highest water holding capacity (WHC) and oil holding capacity (OHC). This was attributed to the disulfide bonds created in the proteins by the ultrasound treatment, encouraging them to interact to form more uniform holes in gel that can hold more water/oil molecules. Conversely, at pH 4.5, the WHCs of the gels were reduced due to the presence of rougher protein structures. These findings shed light on the impact of protein composition on gel properties and offer insights into enhancing the quality of quinoa protein gel. Full article